Kupffer cell ablation improves hepatic microcirculation after trauma and sepsis.

BACKGROUND: Macrophages undergo maladaptive alterations after trauma. In this study, we assessed the role of Kupffer cells in hepatic microcirculatory response to endothelin-1 (ET-1) after femur fracture (FFx) and cecal ligation and puncture (CLP). METHODS: Sprague-Dawley rats (200-300 g) underwent sham, FFx, CLP, or FFx + CLP. To ablate Kupffer cells, group 1 animals were treated with gadolinium chloride, and group 2 animals received saline. Hepatic microcirculation was assessed by intravital microscopy. Liver mitochondrial redox state and tissue oxygen (tPo2) were determined by NADH and ruthenium fluorescence, respectively. Liver damage was estimated by alanine aminotransferase levels. Differences were assessed using analysis of variance followed by Student-Newman-Keuls post hoc test. RESULTS: After 10 minutes of ET-1, CLP and FFx + CLP caused significant reduction in hepatic perfusion index (2.5-fold and 5-fold vs. sham, p < 0.05, respectively), redox state (36% and 45% vs. sham, p < 0.01, respectively), tPo2 (10% and 12% vs. sham, p < 0.05, respectively), and more liver damage compared with sham and FFx-treated animals. Kupffer cell depletion restored microcirculation, redox state, and tPo2 and abrogated hepatocellular damage. CONCLUSION: Kupffer cells contribute directly to hepatic microcirculatory dysfunction and liver injury after inflammatory stress. Furthermore, Kupffer cell depletion ameliorates the microcirculatory perturbations of trauma and sepsis. Thus, modulation of Kupffer cell response may prove beneficial.

Kupffer cell ablation attenuates cyclooxygenase-2 expression after trauma and sepsis.

BACKGROUND: Prostaglandins, synthesized by cyclooxygenase (COX), play an important role in the pathophysiology of inflammation. Severe injuries result in immunosuppression, mediated, in part, by maladaptive changes in macrophages. Herein, we assessed Kupffer cell-mediated cyclooxygenase-2 (COX-2) expression on liver function and damage after trauma and sepsis. MATERIALS AND METHODS: To ablate Kupffer cells, Sprague Dawley rats were treated with gadolinium chloride (GdCl3) 48 and 24 h before experimentation. Animals then underwent femur fracture (FFx) followed 48 h later by cecal ligation and puncture (CLP). Controls received sham operations. After 24 h, liver samples were obtained, and mRNA and protein expression were determined by PCR, Western blot, and immunohistochemistry. Indocyanine-Green (ICG) clearance and plasma alanine aminotransferase (ALT) levels were determined to assess liver function and damage, respectively. One-way analysis of variance (ANOVA) with Student-Newman-Keuls test was used to assess statistical significance. RESULTS: After CLP alone, FFx+CLP, and GdCl3+FFx+CLP, clearance of ICG decreased. Plasma ALT levels increased in parallel with severity of injury. Kupffer cell depletion attenuated the increased ALT levels after FFx+CLP. Femur fracture alone did not alter COX-2 protein compared with sham. By contrast, COX-2 protein increased after CLP and was potentiated by sequential stress. Again, Kupffer cell depletion abrogated the increase in COX-2 after sequential stress. Immunohistochemical data confirmed COX-2 positive cells to be Kupffer cells. CONCLUSIONS: In this study, sequential stress increased hepatic COX-2 protein. Depletion of Kupffer cells reduced COX-2 and attenuated hepatocellular injuries. Our data suggest that Kupffer cell-dependent pathways may contribute to the inflammatory response leading to increased mortality after sequential stress.